Crossfire would help in the future if you get a monitor that does like 1920x1200 or higher.

With 1680x1050 a single HD4850 would be fine for the majority of games on maximum settings though perhaps with little/none AA. Looks like you have some money though so a HD4870 1GB would be a better choice. No point in getting a 512MB 4870 when it isn't much cheaper. Also the 1GB 4870 would be able to hold its own on a 24" LCD too.

Also depending on how much storage you need, you might consider the WD 640GB instead as it performs just as well as the 320GB (assuming you get a single platter one). All the 640s though are pretty much guaranteed to be dual 320GB platters these days.

As for ATI drivers, they are overall fine and Catalyst 9.1 is supposed to fix a ton of things however it's been delayed since they found more bugs. The real issues arise with Crossfire IMO, single cards are fine.

That 750W Corsair PSU will be good, especially if you move to Crossfire at some point.

I'm not sure if that whole "Dragon" platform marketing scheme means anything or not. Even if it does, it's probably minimal gains.

Oh and if you plan to OC, I'd definitely suggest some form of aftermarket cooling like the OCZ Vendetta 2 or other various HDT (heatpipe direct touch) heatsinks.